December 28, 2009
We have detected only one transiting planet that has a mass below 10 Earth masses. This world, CoRoT-7b (named after the European Convection, Rotation and planetary Transits satellite) has a radius 1.7 times that of Earth. The planet is just around 4.8 times Earth's mass. This gives it a density about the same as Earth's, implying that it is likely rocky in composition. This makes CoRoT-7b the only confirmed rocky extrasolar planet, and therefore the largest exoplanet of this composition.
CoRoT-7b (in the foreground of this illustration), is the only confirmed rocky exoplanet. It orbits so close to its star that its surface is likely molten rock.
Photo by ESO/L. Calcada
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